Agricultural Research Service researchers develop “hardy” yeast for cellulosic ethanol production

In Illinois, yeasts play a key role in converting (“fermenting”) sugars from plants into ethanol fuel. But not all yeasts are created equal. Some are better fermenters than others because they can tolerate the harsh conditions of the bioreactors in which they’re used. 

Clavispora NRRL Y-50464 is just such a yeast. A team of Agricultural Research Service (ARS) scientists at the agency’s National Center for Agricultural Utilization Research in Peoria, Illinois, used a standard microbiology procedure called “adaptive laboratory evolution” to generate the hardy yeast strain, which in tests outperformed the industry standard, Saccharomyces cerevisiae.

The strain is the toughest of the tough selected by the researchers from a natural population of Clavispora yeasts originally found growing on sweet sorghum. This toughness includes heat tolerance, fast growth and an ability to detoxify harmful byproducts like furfural while producing ethanol. The yeast strain also makes its own beta-glucosidase, an enzyme which catalyzes the breakdown of simple sugars like glucose from lignocellulose so they can be fermented into ethanol. This eliminates the need to add beta-glucosidase.